The 'Trojan' SMS dialler infecting mobile phones running pirate copies of the "Mosquitos" game is not actually a Trojan at all but rather a botched copy-protection feature of the original game...

Earlier this week mobile operating system maker Symbian warned that illegal versions of the game contain a Trojan that sends costly SMS text messages to premium rate lines without the owner realising it until the bill arrives.

But, in a startling twist, it has now emerged that the premium rate SMS functionality was put in the game from the beginning by the original manufacturer.

Mikko Hypponen, head of antivirus labs at F-Secure, said there is no "cracked" version of the game because nothing has been added to the code in the illegal game, which is still available on P2P networks.

"There was nothing to crack as there was no copy protection," he said.